Merge pull request #123 from JiandanDream/master

[swift][add] From 06 to 09.

swift/06_linkedlist/SinglyLinkedList.swift

@@ -0,0 +1,128 @@
+//
+//  Created by Jiandan on 2018/10/12.
+//  Copyright © 2018 Jiandan. All rights reserved.
+//
+
+import Foundation
+
+class Node<T> {
+    var value: T?
+    var next: Node?
+    
+    init(){}
+    
+    init(value: T) {
+        self.value = value
+    }
+}
+
+/// 单链表
+/// 实现插入、删除、查找操作
+class List<Element: Equatable> {
+    private var dummy = Node<Element>() // 哨兵结点，不存储数据
+    var size: Int {
+        var num = 0
+        var tmpNode = dummy.next
+        while tmpNode != nil {
+            num += 1
+            tmpNode = tmpNode!.next
+        }
+        return num
+    }
+    var isEmpty: Bool { return size > 0 }
+    
+    /// find node with value
+    func node(with value: Element) -> Node<Element>? {
+        var node = dummy.next
+        while node != nil {
+            if node!.value == value {
+                return node
+            }
+            node = node!.next
+        }
+        
+        return nil
+    }
+    // 约定：链表的 index 从 1 开始
+    func node(at index: Int) -> Node<Element>? {
+        var num = 1
+        var node = dummy.next
+        while node != nil {
+            if num == index {
+                return node
+            }
+            node = node!.next
+            num += 1
+        }
+        return nil
+    }
+    
+    func insertToHead(value: Element) {
+        let newNode = Node(value: value)
+        return insertToHead(node: newNode)
+    }
+    
+    func insertToHead(node: Node<Element>) {
+        node.next = dummy.next
+        dummy.next = node
+    }
+    
+    func insert(after node: Node<Element>, newValue: Element) {
+        let newNode = Node(value: newValue)
+        return insert(after: node, newNode: newNode)
+    }
+
+    func insert(after node: Node<Element>, newNode: Node<Element>) {
+        newNode.next = node.next
+        node.next = newNode
+    }
+    
+    func insert(before node: Node<Element>, newValue: Element) {
+        let newNode = Node(value: newValue)
+        return insert(before: node, newNode: newNode)
+    }
+    
+    func insert(before node: Node<Element>, newNode: Node<Element>) {
+        var lastNode = dummy
+        var tmpNode = dummy.next
+
+        while tmpNode != nil {
+            if tmpNode === node {
+                newNode.next = tmpNode
+                lastNode.next = newNode
+                break
+            }
+            lastNode = tmpNode!
+            tmpNode = tmpNode!.next
+        }
+    }
+    
+    func delete(node: Node<Element>) {
+        var lastNode = dummy
+        var tmpNode = dummy.next
+
+        while tmpNode != nil {
+            if tmpNode === node {
+                lastNode.next = tmpNode!.next
+                break
+            }
+
+            lastNode = tmpNode!
+            tmpNode = tmpNode!.next
+        }
+    }
+    /// 删除首个 value 符合要求的结点
+    func delete(value: Element) {
+        var lastNode = dummy
+        var tmpNode = dummy.next
+        while tmpNode != nil {
+            if tmpNode!.value == value {
+                lastNode.next = tmpNode!.next
+                break
+            }
+
+            lastNode = tmpNode!
+            tmpNode = tmpNode!.next
+        }
+    }
+}

swift/07_linkedlist/LinkedListAlgo.swift

@@ -0,0 +1,111 @@
+//
+// Created by Jiandan on 2018/10/13.
+// Copyright (c) 2018 Jiandan. All rights reserved.
+//
+
+/**
+ * 1) 单链表反转
+ * 2) 链表中环的检测
+ * 3) 两个有序的链表合并
+ * 4) 删除链表倒数第n个结点
+ * 5) 求链表的中间结点
+ */
+import Foundation
+/// 单链表反转
+func reverseSinglyLinkedList<Element>(head: Node<Element>) -> Node<Element>? {
+    var reverseHead: Node<Element>?, currentNode: Node<Element>?, prevNode: Node<Element>?
+    currentNode = head
+    while currentNode != nil {
+        let nextNode = currentNode!.next
+        if nextNode == nil {
+            reverseHead = currentNode
+        }
+        currentNode!.next = prevNode
+        prevNode = currentNode
+        currentNode = nextNode
+    }
+    return reverseHead
+}
+/// 检测环
+func hasCircle<Element>(head: Node<Element>) -> Bool {
+    var fast = head.next
+    var slow: Node<Element>? = head
+    while fast != nil {
+        if fast === slow {
+            return true
+        }
+        fast = fast!.next?.next
+        slow = slow!.next
+    }
+    return false
+}
+/// 两个有序的链表合并
+func mergeSortedLists<Element: Comparable>(headA: Node<Element>?, headB: Node<Element>?) -> Node<Element>? {
+    guard let headA = headA else {
+        return headB
+    }
+    guard let headB = headB else {
+        return headA
+    }
+    
+    var head: Node<Element>?, tail: Node<Element>?
+    var nodeA: Node<Element>? = headA, nodeB: Node<Element>? = headB
+    if nodeA!.value! < nodeB!.value! {
+        head = nodeA
+        nodeA = nodeA!.next
+    } else {
+        head = nodeB
+        nodeB = nodeB!.next
+    }
+    tail = head
+    
+    while nodeA != nil, nodeB != nil {
+        if nodeA!.value! < nodeB!.value! {
+            tail!.next = nodeA
+            nodeA = nodeA!.next
+        } else {
+            tail!.next = nodeB
+            nodeB = nodeB!.next
+        }
+        tail = tail!.next
+    }
+    
+    if nodeA != nil {
+        tail?.next = nodeA
+    } else {
+        tail?.next = nodeB
+    }
+
+    return head
+}
+
+/// 删除倒数第n个结点
+func deleteNode<Element>(at lastNum: Int, in head: Node<Element>) {
+    var slow: Node<Element>? = head
+    var fast: Node<Element>? = head
+    var num = 1
+    while fast != nil, num < lastNum {
+        fast = fast!.next
+        num += 1
+    }
+
+    var prevNode: Node<Element>?
+    while fast != nil {
+        prevNode = slow
+        fast = fast!.next
+        slow = slow!.next
+    }
+    prevNode?.next = slow?.next
+}
+
+/// 求链表的中间结点
+func halfNode<Element>(in head: Node<Element>) -> Node<Element>? {
+    var slow: Node<Element>? = head
+    var fast: Node<Element>? = head
+
+    while fast?.next != nil, fast?.next?.next != nil {
+        fast = fast!.next?.next
+        slow = slow!.next
+    }
+    return slow
+}

swift/08_stack/Browser.swift

@@ -0,0 +1,27 @@
+//
+// Created by Jiandan on 2018/10/12.
+// Copyright (c) 2018 Jiandan. All rights reserved.
+//
+
+import Foundation
+
+struct Page {
+    /// 存储前进 url
+    private var forwardArray = [String]()
+    /// 存储后退 url
+    private var backArray = [String]()
+    
+    var currentURL: String? { return forwardArray.last }
+
+    init(url: String) {
+        forwardArray.append(url)
+    }
+    /// 前进
+    mutating func goForward(url: String) {
+        forwardArray.append(url)
+    }
+    /// 后退
+    mutating func goBack() {
+        backArray.append(forwardArray.popLast()!)
+    }
+}

swift/08_stack/BrowserDemo.swift

@@ -0,0 +1,27 @@
+//
+// Created by Jiandan on 2018/10/12.
+// Copyright (c) 2018 Jiandan. All rights reserved.
+//
+
+import Foundation
+
+struct Page {
+    /// 存储前进 url
+    private var forwardArray = [String]()
+    /// 存储后退 url
+    private var backArray = [String]()
+    
+    var currentURL: String { return forwardArray.last! }
+
+    init(url: String) {
+        forwardArray.append(url)
+    }
+    /// 前进
+    mutating func goForward(url: String) {
+        forwardArray.append(url)
+    }
+    /// 后退
+    mutating func goBack() {
+        backArray.append(forwardArray.popLast()!)
+    }
+}

swift/08_stack/Stack.swift

@@ -0,0 +1,21 @@
+//
+// Created by Jiandan on 2018/10/12.
+// Copyright (c) 2018 Jiandan. All rights reserved.
+//
+
+import Foundation
+
+protocol Stack {
+    /// 持有的数据类型
+    associatedtype Element
+    /// 是否为空
+    var isEmpty: Bool { get }
+    /// 队列大小
+    var size: Int { get }
+    /// 返回队列头部元素
+    var peek: Element? { get }
+    /// 入栈
+    mutating func push(newElement: Element) -> Bool
+    /// 出栈
+    mutating func pop() -> Element?
+}

swift/08_stack/StackBasedOnLinkedList.swift

@@ -0,0 +1,37 @@
+//
+// Created by Jiandan on 2018/10/12.
+// Copyright (c) 2018 Jiandan. All rights reserved.
+//
+
+import Foundation
+
+struct StackBasedOnLinkedList<Element>: Stack {
+    private var head = Node<Element>() // 哨兵结点，不存储内容
+    
+    // MARK: Protocol: Stack
+    
+    var isEmpty: Bool { return head.next == nil }
+    
+    var size: Int {
+        var count = 0
+        while head.next != nil {
+            count += 1
+        }
+        return count
+    }
+    
+    var peek: Element? { return head.next?.value }
+    
+    func push(newElement: Element) -> Bool {
+        let node = Node(value: newElement)
+        node.next = head.next
+        head.next = node
+        return true
+    }
+    
+    func pop() -> Element? {
+        let node = head.next
+        head.next = node?.next
+        return node?.value
+    }
+}

swift/09_queue/ArrayQueue.swift

@@ -6,9 +6,7 @@
 import Foundation
 
 /// 用数组实现的队列
-struct ArrayQueue<T>: Queue {
-    typealias Element = T
-    
+struct ArrayQueue<Element>: Queue {
     /// 数组
     private var items: [Element]
     /// 数组最大长度
@@ -78,9 +76,7 @@ struct ArrayQueue<T>: Queue {
 
 /// 使用2个数组实现无界队列，用到 Swift 中 Array 较多的方法
 /// 来源：《iOS 面试之道》（故胤道长，唐巧）
-struct ArrayQueue2<T>: Queue {
-    typealias Element = T
-    
+struct ArrayQueue2<Element>: Queue {
     /// 输入数组，主要负责入队
     var inArray = [Element]()
     /// 输出数组，主要负责出队

swift/09_queue/CircularQueue.swift

@@ -6,9 +6,7 @@
 import Foundation
 
 /// 循环队列
-struct CircularQueue<T>: Queue {
-    typealias Element = T
-
+struct CircularQueue<Element>: Queue {
     /// 数组
     private var items: [Element]
     /// 数组最大长度

swift/09_queue/QueueBasedOnLinkedList.swift

@@ -5,18 +5,7 @@
 
 import Foundation
 
-class Node<T> {
-    var value: T?
-    var next: Node?
-    
-    init(value: T) {
-        self.value = value
-    }
-}
-
-struct QueueBasedOnLinkedList<T>: Queue {
-    typealias Element = T
-    
+struct QueueBasedOnLinkedList<Element>: Queue {
     /// 队首
     var head: Node<Element>?
     /// 队尾
@@ -27,10 +16,15 @@ struct QueueBasedOnLinkedList<T>: Queue {
     var isEmpty: Bool { return head == nil }
     
     var size: Int {
-        var count = 0
+        if isEmpty {
+            return 0
+        }
+        
+        var count = 1 // head 本身算一个
         while head?.next != nil {
             count += 1
         }
+        
         return count
     }